The CERAD Neuropathology Task Force will refine and improve the CERAD neuropathology protocol from the standardized, reliable, and practical evaluation of autopsy brains from dementia and control subjects. A long range goal is to improve the quality of the neuropathology assessment of autopsy brains from demented patients by neuropathologists and non- specialist pathologists. Our revised data entry form and illustrated guidebook will facilitate inclusion of information on a broad spectrum of pathological changes associated with AD. Analysis of the data will lead to development of more accurate and reliable neuropathological criteria, characterization of clinical-pathological subsets, and understanding of the range of changes in AD. Clinical-pathological correlation on CERAD subjects will be emphasized by correlating neuropathology data with clinical and neuropsychological information on demented and control subjects. Issues such as the relationship of extrapyramidal signs and Parkinson's disease changes in AD, the spectra of Parkinson's disease related disorders such as diffuse Lewy body disease, as well as the nature and frequency of AD and its neuropathological basis will be explored. To insure quality control of the CERAD neuropathology assessment, we have instituted several procedures, including an external blinded review of slides without clinical history, and distribution of unknown slides to measure agreement and inter-rater reliability among neuropathologists with regard to diagnoses and histopathological features.